The Reproductive and Developmental Toxicology Research Core is responsible for activities in five sub-specialty areas. These activities range from the development of new laboratory analytical methods to population-based studies of human health. The research activities in this Core take a multi-disciplinary approach to solving problems that have direct relevance to human reproductive health. They involve one or more Facility Core members and usually at least one Facility Core for support. Experimental designs used by Core members include clinical investigations, in vivo studies with animal models, and in vitro mechanistic studies. Historically, this Core has been active in both epidemiological and molecular aspects of reproductive toxicology. For the former aspect, the goal is to develop and apply reliable biomarkers/analytical methods for population-based studies. For the latter aspect, the goal is to understand the mechanism, by which xenobiotics adversely affect the most vulnerable processes of both male and female reproduction.